CHICAGO – Total dietary fats and saturated fatty acids were found to be positively associated with esophageal adenocarcinoma, but not with Barrett’s esophagus, in a prospective cohort study reported at the annual Digestive Disease Week.
"The role of fats may therefore be important in the change from metaplasia into neoplasia," said principal investigator Dr. Max Yates of the Norfolk and Norwich (England) University Hospital. "Dietary fats and saturated fats should therefore be measured in future etiological studies of adenocarcinoma."
The study, funded by Cancer Research UK and the U.K. Medical Research Council, was intended to evaluate the role of dietary fat in the etiology of Barrett’s esophagus and esophageal adenocarcinoma. Barrett’s esophagus is characterized by metaplastic change in the cells of the lower esophagus, Dr. Yates said, and is recognized as a risk factor for esophageal adenocarcinoma.
A prospective cohort design was selected because the alternative case-control designs are subject to recall bias and selection bias, which can lead to inaccuracies in the dietary information.
The cohort was recruited from the EPIC (European Prospective Investigation into Cancer and Nutrition) Norfolk county database. The EPIC study overall has recruited over 500,000 participants in 10 countries, and the EPIC-Norfolk cohort consists of 23,750 participants (aged 45-74 years) from rural, suburban, and inner-city areas.
There were three groups in the study: 3,667 randomly selected controls, 100 cases of Barrett’s esophagus, and 61 cases of esophageal adenocarcinoma. Controls were about the same age as were patients with Barrett’s esophagus (median, 59-60 years at recruitment), whereas those with esophageal adenocarcinoma were about 7 years older (median, 67 years). More than 80% of both groups were male. In this prospective cohort, the median age at diagnosis was 67 years for the Barrett’s patients and 73 years for the esophageal adenocarcinoma patients.
At enrollment and with the help of a nutritionist, participants began a 7-day food diary, which is "the most accurate, validated form of pragmatic nutritional assessment in large-scale epidemiological studies," said Dr. Yates. Patients recorded all food and beverages consumed, along with brands, portion sizes, and recipes. The diaries were coded using the DINER (Data Into Nutrients for Epidemiological Research) computer program.
Quintiles of dietary fat intake were generated, and hazard ratios were estimated using Cox regression analysis adjusted for age, sex, body mass index, smoking, alcohol use, and total energy intake.
The study population was divided into quintiles of dietary fat intake, and no association was found between total dietary fat intake and the diagnosis of Barrett’s esophagus. However, for esophageal adenocarcinoma, a stepwise increase in risk was observed across all quintiles of fat intake.
"The fifth (or highest) quintile has just under four times greater risk, compared to the lowest," said Dr. Yates, noting that this finding nevertheless did not quite reach statistical significance. However, he said, the trend from one quintile to the next was 50%, and this was statistically significant (hazard ratio, 1.50; 95% confidence interval, 1.05-2.14; P = .03).
The results were similar for saturated fats. No association was found between dietary saturated fat intake and a diagnosis of Barrett’s esophagus. However, there was an increased risk for esophageal adenocarcinoma with greater saturated fat intake.
"The fifth (highest) quintile had around three times greater risk, compared to the lowest," said Dr. Yates. The trend, or average increase between quintiles, was statistically significant (HR, 1.35; 95% CI, 1.01-1.85; P = 04).
Dr. Yates concluded that total fats and saturated fatty acids were positively associated with esophageal adenocarcinoma, but not with Barrett’s esophagus. "This has been demonstrated for the first time using food diaries, in a prospective cohort," he said, adding that fats may play a role in the transition of tissue from metaplasia to neoplasia. The study is ongoing, with a goal of assessing many different dietary factors, to determine whether they are involved in the development of this type of cancer.
The study was funded by Cancer Research UK and the U.K. Medical Research Council. Dr. Yates stated that he had no relevant financial disclosures.